Lösung für Tag 15, Teil 2

1 files changed, 46 insertions, 2 deletions

diff --git a/src/day15.cpp b/src/day15.cpp
index 905110f..607f5f2 100644
--- a/src/day15.cpp
+++ b/src/day15.cpp
@@ -1,5 +1,7 @@
+#include <algorithm>
 #include <fstream>
 #include <iostream>
+#include <list>
 #include <sstream>
 #include <string>
 #include <vector>
@@ -46,8 +48,8 @@ calculate_hash(string_view str)
 void
 part1()
 {
-        const auto line  = read_file("data/day15.txt");
-        const auto parts = split(line, ',');
+        const auto    line  = read_file("data/day15.txt");
+        const auto    parts = split(line, ',');
         unsigned long value = 0;
         for ( const auto& part: parts ) {
                 value += calculate_hash(part);
@@ -55,8 +57,50 @@ part1()
         cout << value << endl;
 }
 
+void
+part2()
+{
+        vector<list<tuple<string, long>>> boxes(256);
+
+        const auto line  = read_file("data/day15.txt");
+        const auto parts = split(line, ',');
+        for ( const auto& part: parts ) {
+                const auto pos  = part.find_first_of("=-");
+                const auto lens = part.substr(0, pos);
+                auto&      box  = boxes[calculate_hash(lens)];
+
+                if ( part[pos] == '=' ) {
+                        const auto value = stol(part.substr(pos + 1));
+
+                        auto iter = find_if(box.begin(), box.end(), [&lens](const auto& element) { return get<0>(element) == lens; });
+                        if ( iter == box.end() ) {
+                                box.emplace_back(lens, value);
+                        }
+                        else {
+                                *iter = { lens, value };
+                        }
+                }
+                else {
+                        box.remove_if([&lens](const auto& element) { return get<0>(element) == lens; });
+                }
+        }
+
+        long value = 0;
+        for ( size_t idx = 0; idx != boxes.size(); ++idx ) {
+                const auto& box = boxes[idx];
+
+                long lens_number = 1;
+                for ( const auto& lens: box ) {
+                        value += static_cast<long>(idx + 1) * lens_number * get<1>(lens);
+                        ++lens_number;
+                }
+        }
+        cout << value << endl;
+}
+
 int
 main()
 {
         part1();
+        part2();
 }